Schistosoma mansoni is a parasitic infection common in the tropics and
sub-tropics. Chronic and advanced disease includes abdominal pain,
diarrhoea, blood in the stool, liver cirrhosis, portal hypertension, and
To evaluate the effects of antischistosomal drugs, used alone or in
combination, for treating S. mansoni infection.
We searched MEDLINE, EMBASE and LILACS from inception to October 2012,
with no language restrictions. We also searched the Cochrane Infectious
Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2012)
and mRCT. The reference lists of articles were reviewed and experts were
contacted for unpublished studies.
Randomized controlled trials of antischistosomal drugs, used alone or
in combination, versus placebo, different antischistosomal drugs, or
different doses of the same antischistosomal drug for treating S.
Data collection and analysis
One author extracted data and assessed eligibility and risk of bias in
the included studies, which were independently checked by a second
author. We combined dichotomous outcomes using risk ratio (RR) and
continuous data weighted mean difference (WMD); we presented both with
95% confidence intervals (CI). We assessed the quality of evidence using
the GRADE approach.
Fifty-two trials enrolling 10,269 participants were included. The
evidence was of moderate or low quality due to the trial methods and
small numbers of included participants.
Compared to placebo, praziquantel 40 mg/kg probably reduces
parasitological treatment failure at one month post-treatment (RR 3.13,
95% CI 1.03 to 9.53, two trials, 414 participants, moderate quality
evidence). Compared to this standard dose, lower doses may be inferior
(30 mg/kg: RR 1.52, 95% CI 1.15 to 2.01, three trials, 521 participants,
low quality evidence; 20 mg/kg: RR 2.23, 95% CI 1.64 to 3.02, two
trials, 341 participants, low quality evidence); and higher doses, up to
60 mg/kg, do not appear to show any advantage (four trials, 783
participants, moderate quality evidence).
The absolute parasitological cure rate at one month with praziquantel 40
mg/kg varied substantially across studies, ranging from 52% in Senegal
in 1993 to 92% in Brazil in 2006/2007.
Compared to placebo, oxamniquine 40 mg/kg probably reduces
parasitological treatment failure at three months (RR 8.74, 95% CI 3.74
to 20.43, two trials, 82 participants, moderate quality evidence). Lower
doses than 40 mg/kg may be inferior at one month (30 mg/kg: RR 1.78, 95%
CI 1.15 to 2.75, four trials, 268 participants, low quality evidence; 20
mg/kg: RR 3.78, 95% CI 2.05 to 6.99, two trials, 190 participants, low
quality evidence), and higher doses, such as 60 mg/kg, do not show a
consistent benefit (four trials, 317 participants, low quality
These trials are now over 20 years old and only limited information was
provided on the study designs and methods.
Praziquantel versus oxamniquine
Only one small study directly compared praziquantel 40 mg/kg with
oxamniquine 40 mg/kg and we are uncertain which treatment is more
effective in reducing parasitological failure (one trial, 33
participants, very low quality evidence). A further 10 trials compared
oxamniquine at 20, 30 and 60 mg/kg with praziquantel 40 mg/kg and did
not show any marked differences in failure rate or percent egg
We are uncertain whether combining praziquantel with artesunate reduces
failures compared to praziquantel alone at one month (one trial, 75
participants, very low quality evidence).
Two trials also compared combinations of praziquantel and oxamniquine in
different doses, but did not find statistically significant differences
in failure (two trials, 87 participants).
Other outcomes and analyses
In trials reporting clinical improvement evaluating lower doses (20
mg/kg and 30 mg/kg) against the standard 40 mg/kg for both praziquantel
or oxamniquine, no dose effect was demonstrable in resolving abdominal
pain, diarrhoea, blood in stool, hepatomegaly, and splenomegaly (follow
up at one, three, six, 12, and 24 months; three trials, 655
Adverse events were not well-reported but were mostly described as minor
In an additional analysis of treatment failure in the treatment arm of
individual studies stratified by age, failure rates with 40 mg/kg of
both praziquantel and oxamniquine were higher in children.
Praziquantel 40 mg/kg as the standard treatment for S. mansoni
infection is consistent with the evidence. Oxamniquine, a largely
discarded alternative, also appears effective.
Further research will help find the optimal dosing regimen of both these
drugs in children.
Combination therapy, ideally with drugs with unrelated mechanisms of
action and targeting the different developmental stages of the
schistosomes in the human host should be pursued as an area for future
Plain Language Summary
Schistosoma mansoni is a parasitic worm common in Africa, the Middle
East and parts of South America. The worm larvae live in ponds and lakes
contaminated by faeces, and can penetrate a persons’ skin when they swim
or bathe. Inside the host, the larvae grow into adult worms; these
produce eggs, which are excreted in the faeces. Eggs rather than worms
cause disease. Long-term infection can cause bloody diarrhoea, abdominal
pains, and enlargement of the liver and spleen.
In this review, researchers in the Cochrane Collaboration evaluated drug
treatments for people infected with Schistosoma mansoni. After searching
for all relevant studies, they found 52 trials, including 10,269 people,
conducted in Africa, Brazil and the Middle East. Most trials report on
whether or not the treatment stops eggs excretion; three reported the
persons recovery from symptoms.
The results show that a single dose of praziquantel (40 mg/kg), as
recommended by the World Health Organization, is an effective treatment
for Schistosoma mansoni infection. Lower doses may be less effective,
and higher doses probably have no additional benefit.
Oxamniquine (40 mg/kg), though now rarely used, is also effective.
Again, lower doses may be less effective and no advantage has been
demonstrated with higher doses.
Only one study directly compared praziquantel 40 mg/kg with oxamniquine
40 mg/kg, and based on this limited evidence, we are uncertain which
intervention is more effective. Adverse events were not well reported
for either drug, but were mostly described as minor and transient.
In children aged less than 5 years, there is limited evidence that these
doses may be less effective, and further research will help optimise the
dose for this age-group.
Danso-Appiah, A.; Olliaro, P.L.; Donegan, S.; Sinclair, D.; Utzinger, J. Drugs for treating Schistosoma mansoni infection. Cochrane Database of Systematic Reviews (2013) Issue 2, Art. No.: CD000528. [DOI: 10.1002/14651858.CD000528.pub2]
Drugs for treating Schistosoma mansoni infection